From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 93DB52F6FAD; Thu, 17 Jul 2025 16:54:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752771277; cv=none; b=CKWaE9LFuB4HXoWt2x12y1UcdqhhqXuhQYdFmWFOe5SMrVvQZPvYA/nTSC9wjaelPvfGpXNvUuh/l9j/vAKCrH38Py53WMxUSupIw3HUeihkJdOwAWixUGbTFvStRYU3Qf3Mid33AI2AaIpH9zkulGcb9rA4qsrMzPbY9j9b3YI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752771277; c=relaxed/simple; bh=wltZfUVemhVqBJv2X+OS136Vc8QdzWWBDDT2yFGTmVQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=HAgfBZAT1OQI3YWDJ6c+JYRZRd0lrvdJxzcq4uPE1U9cfwqo80dOI5+ovGjzdRI+iixKrBTZB177Uzilpa+aR888TcA2gdNGB4aBxB5ZQYa9KV9+xTFsiJlqWkgoH4bqL9odbv0Xpl0XVp8N9+mBaUdClboVQ5i+ap+HQqPsyto= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fqG5RH84; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fqG5RH84" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06DB8C4CEE3; Thu, 17 Jul 2025 16:54:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752771277; bh=wltZfUVemhVqBJv2X+OS136Vc8QdzWWBDDT2yFGTmVQ=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=fqG5RH84Fm+Gibjk6PACO1WmcIkOKhWjUH2BIZIpdSJFAtmhrpeJV6cPKkTFBG20/ 6/7ejXdvkZmuyWGZrm6jsC4kLZmxcHEdZ8WMmyoNE2ZLByeUofdtG3p/HuNvCkKyCF AFEsm4pLGhE6RkUBU09eJc/EuH92coBUgUUi8VBp0zpWPio/txAIrqq9jVOYwRjSNu Qgp+Ie/hjqgFZIxmHxXpT1peSbCngph7IpTslaARBZZtC9M6IRtHC4on0yUnMDiekf 6WrSVUf1kL+VBD7wZU0O3TM7jStjE7mUTDHsB+1OEdYNk+92bqHKSiqPlDQ2MbtSsI Xw+j6vTCg/+6w== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 9E8D8CE0B77; Thu, 17 Jul 2025 09:54:36 -0700 (PDT) Date: Thu, 17 Jul 2025 09:54:36 -0700 From: "Paul E. McKenney" To: Steven Rostedt Cc: Steven Rostedt , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, x86@kernel.org, Masami Hiramatsu , Mathieu Desnoyers , Josh Poimboeuf , Peter Zijlstra , Ingo Molnar , Jiri Olsa , Namhyung Kim , Thomas Gleixner , Andrii Nakryiko , Indu Bhagat , "Jose E. Marchesi" , Beau Belgrave , Jens Remus , Linus Torvalds , Andrew Morton , Jens Axboe , Florian Weimer , Sam James Subject: Re: [PATCH v14 09/12] unwind deferred: Use SRCU unwind_deferred_task_work() Message-ID: <3eec6c5d-2e4c-41c0-ac43-6df51faeb670@paulmck-laptop> Reply-To: paulmck@kernel.org References: <20250717004910.297898999@kernel.org> <20250717004957.918908732@kernel.org> <47c3b0df-9f11-4e14-97e2-0f3ba3b09855@paulmck-laptop> <20250717082526.7173106a@gandalf.local.home> <41c204c0-eabc-4f4f-93f4-2568e2f962a9@paulmck-laptop> <20250717121010.4246366a@batman.local.home> <20250717123835.21c8aa89@batman.local.home> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250717123835.21c8aa89@batman.local.home> On Thu, Jul 17, 2025 at 12:38:35PM -0400, Steven Rostedt wrote: > On Thu, 17 Jul 2025 09:27:34 -0700 > "Paul E. McKenney" wrote: > > > > Two, I'm still grasping at the concept of srcu_fast (and srcu_lite for > > > that matter), where I rather be slow and safe than optimize and be > > > unsafe. The code where this is used may be faulting in user space > > > memory, so it doesn't need the micro-optimizations now. > > > > Straight-up SRCU and guard(srcu), then? Both are already in mainline. > > > > Or are those read-side smp_mb() calls a no-go for this code? > > As I stated, the read-side is likely going to be faulting in user space > memory. I don't think one or two smp_mb() will really make much of a > difference ;-) > > It's not urgent. If it can be switched to srcu_fast, we can do it later. Very good, we will continue with our removal of SRCU-lite, and I might as well add guard(srcu_fast) in my current series. Thanx, Paul